MacBook Pro A1990 15 2019, motherboard 820-01814-A, won't turn on.

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  • evandrocarlosv
    Evandro Carlos
    • Feb 2018
    • 5
    • Brasil

    #1

    MacBook Pro A1990 15 2019, motherboard 820-01814-A, won't turn on.

    I have this machine, one of the few that arrives on the bench without a short on PPBUS_G3H. At least these voltages are present. I also have the PP3V3 voltage on L7660 and P5VG3 on L7600. I'm not used to dealing with machines where the shorts are not on PPBUS_G3H, so I need help from my colleagues to analyze where this sequence is failing. From what I've measured, the SSD voltages are fine.
    The analyzer shows it as seen in the attached photo.
    Attached Files
  • mon2
    Badcaps Legend
    • Dec 2019
    • 14162
    • Canada

    #2
    Review these threads:

    https://repair.wiki/w/MacBook_Pro_A1..._at_20V_repair

    https://repair.wiki/w/MacBook_Pro_A1990

    Attempt a DFU for which you will require a good battery with a charge since the power adapter is unable to power the logic board.

    Hunt for any parts with a heat signature if you have a thermal camera.

    Comment

    • evandrocarlosv
      Evandro Carlos
      • Feb 2018
      • 5
      • Brasil

      #3
      Thank you for your response, my friend. It seems we have a corrupted firmware. I looked for shorts using the thermal sensor but didn’t find anything abnormal. I only noticed that Q8102 has a slight heating, but nothing exceeding 30/35°C, almost room temperature. I will try the DFU and post the results.

      Comment

      • evandrocarlosv
        Evandro Carlos
        • Feb 2018
        • 5
        • Brasil

        #4
        Unfortunately, the Mac didn’t respond to DFU mode. So, I returned the device because I believe the issue is with the NANDs. I don’t yet perform replacements or programming of them, so I decided to return it.

        Comment

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